The Thai Journal of Veterinary Medicine


Fifteen purebred (Holstein-Friesian) sires and 45 crossbred (75% up-grade Holstein-Friesian) sires from the Division of Artificial Insemination (AI), Department of Livestock Development were genotyped for the kappacasein gene by Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP). The allele A, B and E were found and the allelic frequencies were 0.6, 0.33 and 0.07 in the purebred sires and 0.74, 0.17 and 0.09 in the crossbred sires. The genotypes composed of AA, AB, BB, AE and BE and the genotypic frequencies were 0.34, 0.4, 0.13, 0.13 and 0 in the purebred sires and 0.56, 0.27, 0, 0.11 and 0.06 in the crossbred sires. The Kappa-casein genotype “EE” was not found in this study. The differentiation for allelic and genotypic frequencies between the purebred and the crossbred sires was not significant. Various alleles of the kappa-casein gene and their ratio were revealed. The allele “B” found in this herd will be useful for a sire selection program in the future.

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